The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also be inventions.
Flexible line rotary trimmers are commonly used for cutting vegetation such as grass and weeds, particularly along walks, fences, flower beds, and around trees. These devices may include a rotary driven head that carries one or more lengths of monofilament line mounted within a housing. Extended end portions of each trimmer line projects from each of the housings through guides in the side wall of the housing. As the head rotates at high speeds, the end portion of each of the lines is caused to project outwardly from the housing by the centrifugal forces acting thereon and function as cutting blades. When the cutting line projecting from the head breaks or becomes overly worn, fresh line must be extended from the head and the old line severed and discarded.
Several attempts have been made to provide a more user-friendly rotary cutting head. Such heads typically employ one or more short lengths of a line which are anchored within the head in lieu of the long lengths of line that are wrapped about an interior spool. These heads are frequently referred to as “fixed line cutting heads.” The terms trimmer head and cutting head may be interchanged anywhere they occur in the specification. Similarly the terms trimmer line and cutting line may be interchanged anywhere they appear in the specification.
Although fixed line cutting heads have eliminated the need to carefully wrap a long length of line about the spool, many such heads still require disassembly and reassembly of trimmer head housing parts to replace worn or broken line. In some of these fixed line cutting heads, removal of the worn trimmer line to replace the worn or torn trimmer line with a new fixed length of line can be difficult because the line is “jammed or wedged” so tightly that a tool may be needed and required to aide in unjamming the line to be able to remove it from the trimmer head.
A fixed line head that does not require disassembly to effect line replacement is found in U.S. Pat. No. 4,062,114, issued to Luick and entitled “Vegetation Cutting Apparatus.” The cutting heads disclosed therein are provided with one of several differently configured channels terminating in a reduced diameter portion proximate the side wall of the head. A short length of flexible cutting line extends through the channel and extends radially from the head. The trimmer line is held in place by an enlarged member secured to the inner end of the length of cutting line which is translatable along the channel but cannot pass through the reduced diameter portion thereof. While such a head and line configuration provides for relatively simple line replacement, each length of replacement line must be provided with a suitable enlarged member at one end thereof, significantly increasing the cost of operation. In addition, if the cutting line were to break at the eyelet or outlet end of the line channel, line removal may be difficult.